1. Field of the Invention
The present invention relates to a light source device.
2. Description of the Related Art
A light source device which uses fluorescence is known as a light source device to be suitably combined with an industrial or medical endoscope. For example, Jpn. Pat. Appln. KOKAI Publication No. 2003-19112 discloses an endoscopic apparatus equipped with such a light source device. This endoscopic apparatus is shown in FIG. 10.
An endoscopic insertion portion 100 includes an illumination optical system at the front end. The illumination optical system 103 is connected to an illumination unit 110 through a light guide 101. The illumination unit 110 includes three LED light sources 111, 112, and 113 for emitting ultraviolet light, fluorescent fibers 114, 115, and 116 for respectively generating red light (R light), green light (G light), and blue light (B light) for the radiation of the ultraviolet light emitted from the LED light sources 111, 112, and 113, and dichroic mirrors 117, 118, 119, and 120 for controlling the reflection and transmission of the R light, the G light, and the B light generated from the fluorescent fibers 114, 115, and 116.
The dichroic mirror 117 has a property of reflecting light in the wavelength region of the R light generated from the fluorescent fiber 114. The dichroic mirror 118 has a property of transmitting the light in the wavelength region of the R light generated from the fluorescent fiber 114 and reflecting light in the wavelength region of the G light generated from the fluorescent fiber 115. The dichroic mirror 119 has a property of transmitting light in the wavelength regions of the G light generated from the fluorescent fiber 115 and the R light which has traveled through the fluorescent fiber 115, and reflecting light in the wavelength region of the B light generated from the fluorescent fiber 116. The dichroic mirror 120 has a property of transmitting light in the wavelength regions of the B light generated from the fluorescent fiber 116 and the R light and the G light which have traveled through the fluorescent fiber 116, and reflecting light in the wavelength region of the ultraviolet light (excitation light).
The light in the wavelength regions of the R light, the G light, and the B light which has passed through the dichroic mirror 120 is guided to the illumination optical system 103 by the light guide 101, and radiated from the illumination optical system 103.
In this embodiment, part of the fluorescence generated from the fluorescent fibers 114, 115, and 116, is only used for illumination. That is, the fluorescent or excitation light traveling in the side surface directions of the fluorescent fibers 114, 115, and 116 is radiated from the side surfaces not to be used. Therefore, the efficiency of the use of the excitation light for the generation of fluorescence is low, and the efficiency of the use of the fluorescence for illumination is low.